The present invention relates generally to sewing machines, and more particularly to apparatus for automatically changing therein bobbins and bobbin carriers.
Materials are preferably sewn utilizing lockstitch sewing machines; since, the stitch generated by such a machine is continuously locked, and, accordingly, a small break in the thread will not engender unraveling of the stitch. Due to the nature of this machine, the length of continuous stitch which can be produced is limited by the size of the spool in the bobbin. Because the bobbin of necessity must be fairly small, only a short period of time passes before bobbins must be changed in the sewing machine. Consequently, the use of the lockstitch machine has been limited, particularly in automated equipment. Where large scale production is required, many manufacturers have resorted to employing chain stitch type machines which utilize only a single source of thread. This permits long-term continuous sewing without the inconvenience of necessarily changing the bobbin. The disadvantage of such a machine, however, is that the single thread, if cut or broken, will easily unravel when pulled.
Accordingly, there is a need for an apparatus, which may be incorporated into an automatic process, that permits a lockstitch to be produced on a continuous, uninterrupted basis.